An injector for delivering medicament comprises a collapsible container (1002) for containing the liquid medicament, a normally-closed valve (1004) coupled to the collapsible container (1002) for retaining the liquid medicament within the collapsible container and an injection means (1006) for delivering the liquid medicament from the collapsible container. The liquid medicament is maintained under pressure by a pressurising means (1003) which pressurises the liquid medicament such that it is delivered by the injection means (1006) when the normally-closed valve (1004) is opened.
